Guarding Against the Dangers of Vitamin D Deficiency

By Tiesha D. Johnson, BSN, RN

Vitamin D May Help Prevent Diabetes

Exciting research also indicates a possible therapeutic role for vitamin D in preventing diabetes.

Vitamin D supplementation may reduce susceptibility to type II diabetes by slowing the loss of insulin sensitivity in people who show early signs of the disease. Researchers studied 314 adults without diabetes and gave them either 700 IU of vitamin D and 500 mg of calcium daily or a placebo for three years.73 Among subjects who had impaired (slightly elevated) fasting glucose levels at the study’s onset, those taking the active supplement had a smaller rise in glucose levels over three years than did the controls, as well as a smaller increase in insulin resistance. The researchers concluded that for older adults with impaired glucose levels, supplementing with vitamin D and calcium may help avert metabolic syndrome and type II diabetes.

Type I (insulin-dependent) diabetes is an autoimmune condition, in which the body’s immune system attacks its own insulin-producing pancreatic beta cells. Low vitamin D levels are associated with the development of autoimmune conditions,40,74,75 including type I diabetes,38 and scientists have proposed that vitamin D supplementation may help prevent the disease.76

A very large population-based study in Europe demonstrated the powerful effect of vitamin D supplementation in protecting children against the development of type I diabetes.77 Data from 820 diabetics and 2,335 non-diabetic controls showed that children who received vitamin D supplements in infancy reduced their risk of developing type I diabetes by approximately 33%. The researchers believe that activated vitamin D may protect growing children from autoimmune attack on insulin-producing cells of the pancreas.

Vitamin D May Help Alleviate Depression

It is well established that for people with major depression, symptoms tend to worsen in winter, and also that some people without baseline depression develop depressive symptoms in winter (so-called seasonal affective disorder, or SAD).94,95 Light therapy has been found to be useful for treating wintertime depressive symptoms,96 and it seems likely that at least some of the benefit of light therapy is related to increased activation of vitamin D.

To test this idea, researchers conducted a randomized trial in 15 people with SAD.95 Eight received a single dose of 100,000 IU of vitamin D, and seven received one month of light therapy. All of the supplemented patients—and none of the light-treated patients—had major improvement in depression scores. Interestingly, similar studies using much lower doses of 400-800 IU per day did not yield improvements in SAD symptoms,94,97 again suggesting that we simply need more vitamin D than has been thought.

Vitamin D’s benefits for mental health may not be limited to depression. A 2004 study from Finland98 showed that the risk of developing schizophrenia in adult men was greatly increased in those who had never had vitamin D supplementation as infants, compared to those who had had at least some supplementation. Another recent paper proposes that prenatal vitamin D deficiency could be linked to adult schizophrenia.99 Finally, a laboratory study showed that prenatal vitamin D deprivation was associated with certain behaviors in adult rats that are typical of schizophrenia in humans.100

Vitamin D Provides Essential Immune Support

A recent paper presented persuasive evidence that seasonal infections such as influenza may actually be the result of decreased vitamin D levels,26 not of increased wintertime viral activity, which has been the longstanding conventional wisdom.78 This makes sense, because vitamin D receptors are present on many of the immune system cells responsible for killing viruses and deadly bacteria, and the vitamin—which is less environmentally available in the winter—appears to be a requirement for proper activation of these cells.79,80

A randomized, double-blind study published in 2006 found that vitamin D may support recovery from tuberculosis, a common and deadly infection that most commonly affects the lungs. When patients with moderately advanced tuberculosis supplemented with 0.25 mg (10,000 IU) per day of vitamin D for one week, they had significantly higher rates of improvement than patients who received a placebo.81

Kidney dialysis patients often demonstrate decreased vitamin D levels as well as impaired cellular immune response. Dialysis patients with decreased vitamin D levels and impaired function of anti-viral and anti-cancer natural killer cells experienced substantial increases in natural-killer-cell activity after just one month of supplementation with prescription vitamin D (calcitriol) at 0.5 mcg (20 IU) per day.27 In the laboratory, the same researchers demonstrated that vitamin D treatment of “generalized” white blood cells called monocytes caused them to mature into active natural killer cells within 24 hours.

Further evidence of vitamin D’s ability to bolster protective immune function comes from a laboratory study published earlier this year.82 Researchers discovered that skin cells responding to injury require vitamin D3 to “switch on” vital proteins involved in recognizing and responding to the microbes that cause wound infections. This finding has tremendous implications for preventing and treating wound infections.

Conclusion

Even in people who take vitamin D supplements, the percentage of those with sub-optimal levels remains surprisingly high. Humans cannot arbitrarily consume massive doses of vitamin D (unlike water-soluble nutrients such as vitamin C). For this nutrient, individualized dosing is of particular importance, and the only way to accomplish this is through vitamin D blood testing. With deficiencies likely to be most pronounced following the long winter months, spring is an excellent time to investigate your own vitamin D status.

Detecting deficient levels allows you and your physician to implement vitamin D supplementation to help avert illnesses associated with inadequate vitamin D levels. Optimizing your vitamin D intake may be a safe, low-cost way to protect against cancer, cardiovascular disease, diabetes, immune disorders, and depression, among other serious health conditions.

Vitamin D Basics

Vitamin D occurs in nature in two main forms: vitamin D2, or ergocalciferol, and vitamin D3, or cholecalciferol. While vitamin D2 is obtained from plant sources, vitamin D3 can be either obtained through animal sources, supplements, or synthesized in the skin when its precursor molecule absorbs light energy from ultraviolet B rays.83

In the liver, both vitamin D2 and vitamin D3 are converted into 25-hydroxy-vitamin D, the primary circulating form of vitamin D. Conversion into its active form, 1,25-dihydroxyvitamin D, occurs in the kidney. Pharmaceutical drug forms of activated vitamin D include calcitriol, doxercalciferol, and calcipotriene.83

Supplemental vitamin D is available as vitamin D2 (ergocalciferol) or vitamin D3 (cholecalciferol). Vitamin D2 is only about 20-40% as effective as D3 in maintaining serum concentrations of 25-hydroxyvitamin D, since it is more rapidly broken down in the body. For this reason, vitamin D3 (cholecalciferol) supplements are considered more beneficial than vitamin D2 (ergocalciferol) supplements.7

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